It has been found that, on average, radon constitutes more than half of the normal background radioactivity in the environment. Apparently, radon-222, produced by natural radium in the ground, is responsible. When radon enters a house, either through small fissures, or in well water, it can remain in the air if not ventilated. In such a case, the radon decays to radioactive products that can be absorbed in the lungs and can lead, over a long period of exposure, to lung cancer. It has been estimated that from 5,000 to 20,000 lung cancer deaths annually may be attributed to radon. The U.S. Environmental Protection Agency recommends remedial action if radon levels in homes exceed 4 trillionths of a curie, or 4 picocuries, of radon per liter of air. Although initial discoveries pointed to particular areas susceptible to radon pollution, it is now known that high concentrations exist in many parts of the United States, as well as in a number of European countries.
The recent public awareness concerning the existence of radon gas has brought about a demand for sensitive and accurate detection instruments. At the present, there are numerous commercial offerings of devices intended to detect radon, the devices having varying degrees of effectiveness. All of these devices suffer from one or more of the following problems: (1) lack of sensitivity, (2) slow response time, and (3) high cost.
The present invention provides a radon detection instrument which solves these problems. It is based on technology which is contained in certain U.S. Patents which disclose various devices for the long range detection of alpha particles. The first patent is U.S. Pat. No. 5,184,019, issued Feb. 2, 1993, for a Long Range Alpha Particle Detector. The second is U.S. Pat. No. 5,194,737, issued Mar. 16, 1993, for Single and Double Grid Long Range Alpha Detectors. The third is U.S. Pat. No. 5,187,370, issued Feb. 16, 1993, for Alternating Current Long Range Alpha Particle Detectors. The principle underlying each of these co-pending applications is that alpha particles, although themselves of very short range, create air ions which have a longer range and can be detected with the apparatus disclosed. The present invention modifies this apparatus to provide for reliable detection of radon.
It is therefore an object of the present invention to provide apparatus that can detect radon gas.
It is a further object of the present invention to provide a radon detector which is very sensitive.
It is a still further object of the present invention to provide a radon detector which has a short response time.
It is a feature of the present invention that it can be produced at low cost.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.